A hand lens has the power of 20D. If the letters of a book are to be read with the help of this hand lens, calculate how far from the lens must the book be held.

If the force applied to an object remains constant, is more power needed for the object to move faster ? explain

1. how to locate the image in converging(concave) mirror and diverging (convex) mirror with salt. 2. how to locate the image in a converging (convex) lens and diverging (concave) lens with salt.

Which type of energy would have nothing to do with ironing clothes? a. heat b. chemical c. electrical d. mechanical